34O A. P. MATHEWS. 



CH 3 CH 3 



COOM COOM 



Alanin. 



In any case it will be apparent that the synthetic powers of the 

 cell depend on the same process as the respiratory powers. 



While the interpretation of the exact mechanism by which the 

 respiratory substance or substances (for there may be many such 

 substances in one cell) dissociate water depends, as will be seen, 

 upon Nef's hypothesis and is due to this hypothesis, the general 

 hypothesis that such dissociation of water is taking place and that 

 this is the basis of respiration, is independent of Nef's hypothesis. 

 If, however, that hypothesis be accepted, and of its truth he 

 has already produced so many proofs as to entitle it to pro- 

 visional acceptance, we can go farther and ascribe this most 

 fundamental of living reactions and many protoplasmic syntheses 

 to methylene dissociation, that is, to bivalent carbon particles in 

 protoplasm, as Nef himself has pointed out. Protoplasmic res- 

 piration must in any case be defined in the light of known facts 

 somewhat differently from the ordinary statement. 



Respiration is that process going on in protoplasm by which 

 water is decomposed into oxygen and hydrogen. The oxygen 

 combines with the substances of the protoplasm thus oxidizing 

 them ; the hydrogen is either set free in the gaseous form, or it 

 is united with atmospheric oxygen to form water ; or it combines 

 with other substances in the protoplasm. 



The reaction may be written as follows : 



For anaerobic protoplasm : 



I. R CH 2 OHs->- R CH<;-f H,O 

 II. R CH< + OH 2 s-^R CH = O + H 2 ' 



For aerobic protoplasm : 



I. R' CH 2 OHs-^ R' CH< + H 2 O 



II. R'-CH< + OH 2 + Os-5-R'CH=O + H. 2 O, or 



III. R / 



IV. R' 



1 A great number of reactions of this type are given in Nef's paper already referred 

 to. See also Nef, Journal of the American Chemical Society, Vol. XXVI., 1904, 



P- 1549- 



